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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.rmi.activation;

import java.io.Serializable;
import java.rmi.MarshalledObject;

/**
 * An activation descriptor contains the information necessary to
 * activate an object: <ul>
 * <li> the object's group identifier,
 * <li> the object's fully-qualified class name,
 * <li> the object's code location (the location of the class), a codebase URL
 * path,
 * <li> the object's restart "mode", and,
 * <li> a "marshalled" object that can contain object specific
 * initialization data. </ul>
 *
 * <p>A descriptor registered with the activation system can be used to
 * recreate/activate the object specified by the descriptor. The
 * <code>MarshalledObject</code> in the object's descriptor is passed
 * as the second argument to the remote object's constructor for
 * object to use during reinitialization/activation.
 *
 * @author Ann Wollrath
 * @see java.rmi.activation.Activatable
 * @since 1.2
 */
public final class ActivationDesc implements Serializable {

  /**
   * @serial the group's identifier
   */
  private ActivationGroupID groupID;

  /**
   * @serial the object's class name
   */
  private String className;

  /**
   * @serial the object's code location
   */
  private String location;

  /**
   * @serial the object's initialization data
   */
  private MarshalledObject<?> data;

  /**
   * @serial indicates whether the object should be restarted
   */
  private boolean restart;

  /**
   * indicate compatibility with the Java 2 SDK v1.2 version of class
   */
  private static final long serialVersionUID = 7455834104417690957L;

  /**
   * Constructs an object descriptor for an object whose class name
   * is <code>className</code>, that can be loaded from the
   * code <code>location</code> and whose initialization
   * information is <code>data</code>. If this form of the constructor
   * is used, the <code>groupID</code> defaults to the current id for
   * <code>ActivationGroup</code> for this VM. All objects with the
   * same <code>ActivationGroupID</code> are activated in the same VM.
   *
   * <p>Note that objects specified by a descriptor created with this
   * constructor will only be activated on demand (by default, the restart
   * mode is <code>false</code>).  If an activatable object requires restart
   * services, use one of the <code>ActivationDesc</code> constructors that
   * takes a boolean parameter, <code>restart</code>.
   *
   * <p> This constructor will throw <code>ActivationException</code> if
   * there is no current activation group for this VM.  To create an
   * <code>ActivationGroup</code> use the
   * <code>ActivationGroup.createGroup</code> method.
   *
   * @param className the object's fully package qualified class name
   * @param location the object's code location (from where the class is loaded)
   * @param data the object's initialization (activation) data contained in marshalled form.
   * @throws ActivationException if the current group is nonexistent
   * @throws UnsupportedOperationException if and only if activation is not supported by this
   * implementation
   * @since 1.2
   */
  public ActivationDesc(String className,
      String location,
      MarshalledObject<?> data)
      throws ActivationException {
    this(ActivationGroup.internalCurrentGroupID(),
        className, location, data, false);
  }

  /**
   * Constructs an object descriptor for an object whose class name
   * is <code>className</code>, that can be loaded from the
   * code <code>location</code> and whose initialization
   * information is <code>data</code>. If this form of the constructor
   * is used, the <code>groupID</code> defaults to the current id for
   * <code>ActivationGroup</code> for this VM. All objects with the
   * same <code>ActivationGroupID</code> are activated in the same VM.
   *
   * <p>This constructor will throw <code>ActivationException</code> if
   * there is no current activation group for this VM.  To create an
   * <code>ActivationGroup</code> use the
   * <code>ActivationGroup.createGroup</code> method.
   *
   * @param className the object's fully package qualified class name
   * @param location the object's code location (from where the class is loaded)
   * @param data the object's initialization (activation) data contained in marshalled form.
   * @param restart if true, the object is restarted (reactivated) when either the activator is
   * restarted or the object's activation group is restarted after an unexpected crash; if false,
   * the object is only activated on demand.  Specifying <code>restart</code> to be
   * <code>true</code> does not force an initial immediate activation of a newly registered object;
   * initial activation is lazy.
   * @throws ActivationException if the current group is nonexistent
   * @throws UnsupportedOperationException if and only if activation is not supported by this
   * implementation
   * @since 1.2
   */
  public ActivationDesc(String className,
      String location,
      MarshalledObject<?> data,
      boolean restart)
      throws ActivationException {
    this(ActivationGroup.internalCurrentGroupID(),
        className, location, data, restart);
  }

  /**
   * Constructs an object descriptor for an object whose class name
   * is <code>className</code> that can be loaded from the
   * code <code>location</code> and whose initialization
   * information is <code>data</code>. All objects with the same
   * <code>groupID</code> are activated in the same Java VM.
   *
   * <p>Note that objects specified by a descriptor created with this
   * constructor will only be activated on demand (by default, the restart
   * mode is <code>false</code>).  If an activatable object requires restart
   * services, use one of the <code>ActivationDesc</code> constructors that
   * takes a boolean parameter, <code>restart</code>.
   *
   * @param groupID the group's identifier (obtained from registering
   * <code>ActivationSystem.registerGroup</code> method). The group indicates the VM in which the
   * object should be activated.
   * @param className the object's fully package-qualified class name
   * @param location the object's code location (from where the class is loaded)
   * @param data the object's initialization (activation) data contained in marshalled form.
   * @throws IllegalArgumentException if <code>groupID</code> is null
   * @throws UnsupportedOperationException if and only if activation is not supported by this
   * implementation
   * @since 1.2
   */
  public ActivationDesc(ActivationGroupID groupID,
      String className,
      String location,
      MarshalledObject<?> data) {
    this(groupID, className, location, data, false);
  }

  /**
   * Constructs an object descriptor for an object whose class name
   * is <code>className</code> that can be loaded from the
   * code <code>location</code> and whose initialization
   * information is <code>data</code>. All objects with the same
   * <code>groupID</code> are activated in the same Java VM.
   *
   * @param groupID the group's identifier (obtained from registering
   * <code>ActivationSystem.registerGroup</code> method). The group indicates the VM in which the
   * object should be activated.
   * @param className the object's fully package-qualified class name
   * @param location the object's code location (from where the class is loaded)
   * @param data the object's initialization (activation) data contained in marshalled form.
   * @param restart if true, the object is restarted (reactivated) when either the activator is
   * restarted or the object's activation group is restarted after an unexpected crash; if false,
   * the object is only activated on demand.  Specifying <code>restart</code> to be
   * <code>true</code> does not force an initial immediate activation of a newly registered object;
   * initial activation is lazy.
   * @throws IllegalArgumentException if <code>groupID</code> is null
   * @throws UnsupportedOperationException if and only if activation is not supported by this
   * implementation
   * @since 1.2
   */
  public ActivationDesc(ActivationGroupID groupID,
      String className,
      String location,
      MarshalledObject<?> data,
      boolean restart) {
    if (groupID == null) {
      throw new IllegalArgumentException("groupID can't be null");
    }
    this.groupID = groupID;
    this.className = className;
    this.location = location;
    this.data = data;
    this.restart = restart;
  }

  /**
   * Returns the group identifier for the object specified by this
   * descriptor. A group provides a way to aggregate objects into a
   * single Java virtual machine. RMI creates/activates objects with
   * the same <code>groupID</code> in the same virtual machine.
   *
   * @return the group identifier
   * @since 1.2
   */
  public ActivationGroupID getGroupID() {
    return groupID;
  }

  /**
   * Returns the class name for the object specified by this
   * descriptor.
   *
   * @return the class name
   * @since 1.2
   */
  public String getClassName() {
    return className;
  }

  /**
   * Returns the code location for the object specified by
   * this descriptor.
   *
   * @return the code location
   * @since 1.2
   */
  public String getLocation() {
    return location;
  }

  /**
   * Returns a "marshalled object" containing intialization/activation
   * data for the object specified by this descriptor.
   *
   * @return the object specific "initialization" data
   * @since 1.2
   */
  public MarshalledObject<?> getData() {
    return data;
  }

  /**
   * Returns the "restart" mode of the object associated with
   * this activation descriptor.
   *
   * @return true if the activatable object associated with this activation descriptor is restarted
   * via the activation daemon when either the daemon comes up or the object's group is restarted
   * after an unexpected crash; otherwise it returns false, meaning that the object is only
   * activated on demand via a method call.  Note that if the restart mode is <code>true</code>, the
   * activator does not force an initial immediate activation of a newly registered object;  initial
   * activation is lazy.
   * @since 1.2
   */
  public boolean getRestartMode() {
    return restart;
  }

  /**
   * Compares two activation descriptors for content equality.
   *
   * @param obj the Object to compare with
   * @return true if these Objects are equal; false otherwise.
   * @see java.util.Hashtable
   * @since 1.2
   */
  public boolean equals(Object obj) {

    if (obj instanceof ActivationDesc) {
      ActivationDesc desc = (ActivationDesc) obj;
      return
          ((groupID == null ? desc.groupID == null :
              groupID.equals(desc.groupID)) &&
              (className == null ? desc.className == null :
                  className.equals(desc.className)) &&
              (location == null ? desc.location == null :
                  location.equals(desc.location)) &&
              (data == null ? desc.data == null :
                  data.equals(desc.data)) &&
              (restart == desc.restart));

    } else {
      return false;
    }
  }

  /**
   * Return the same hashCode for similar <code>ActivationDesc</code>s.
   *
   * @return an integer
   * @see java.util.Hashtable
   */
  public int hashCode() {
    return ((location == null
        ? 0
        : location.hashCode() << 24) ^
        (groupID == null
            ? 0
            : groupID.hashCode() << 16) ^
        (className == null
            ? 0
            : className.hashCode() << 9) ^
        (data == null
            ? 0
            : data.hashCode() << 1) ^
        (restart
            ? 1
            : 0));
  }
}
